The order came from a court-appointed receiver.
The order affects about 85 percent of Stanford's U.S. workers, although the receivership said most of Stanford's business and operations "will be discontinued or wound down."
Those staying on the payroll, mainly at Stanford's Houston headquarters, will be involved in the shutdown.
The receivership order says those laid off effective today will receive no severance. Regular salary and benefits will be cut immediately.
The Securities and Exchange Commission has accused Stanford and his finance chief James M. Davis of conducting a "massive Ponzi scheme" through companies they controlled.
An attorney representing Stanford has said his client denies the allegations.
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